Catalytic treatment of hydrocarbons



H. R. wARRlcK M3271 CATALYTIC TREATMENT OF HYDROGARBONS Filed sept. 2v, 1944 INVENTOR ATTORNE oA'rALmo TREATMENT or it ROCARBONS naasten n. 'rm-fiek, west Englewod, N. s., as-

signor to The v'.lexas Company, New York, N. Y., a corporation of Delaware Application September 27, 1944, Serial No. 555,996

' s claims. (ci. 19e-st) This' invention relates to the treatment of hyinvention may readily be practiced in equipment drocarbons with solid catalysts in comminutcd of low cost as compared with either the fixed bed or finely divided form carried on in a plurality or uid type and'consequently is especially adaptof reaction zones with alternating periods of proced for small plants. essing and catalyst regeneration in each zone. For the purpose' of fully explaining the inven- In accordance with thev invention the hydrocartion reference is now had to the accompanying bons in the processing period are owed through drawing which is a diagrammatic `elevation of the reaction zone in contact with catalyst disapparatus adapted for the' practice of the invenpersed or suspended in the owing stream, the tion.

hydrocarbons being continuously removed ,from lo In the drawing a pail f reaCtOrS 0r treating vthe reaction zone while the catalyst is retained chambers A and B are shown. Each chamber therein and in the regenerating step the catalyst is preferably in the form of a vertically disposed is dispersed or suspended in a stream of regenchamber and each is advantageously provided erating fluid to prepare the catalyst for the sucwith an `upper section Ill of enlarged diameter ceeding period of processing. 15 to promote the disengagement of the hydrocar- There may be' said to be two general methods bon vapors from the catalyst. A feed line II has of treatment with solid catalysts, the xed bed valved branches l2 and `i3 extending respectively type and the uid type. In the xed bed method to reactors A and Bvfor supplying the hydrocarbon' the hydrocaubon vapors are passed through a feed. 4A catalyst hopper 1511s provided `forsup-A bed of catalyst; the processing is intermittent beplying powderedor comminuted catalyst to the ing interrupted with periodic intervals of cata- 'reactor in the hydrocarbon feed stream. A valyst regeneration in situ.y In the uid catalyst por line l5 extends from each reactor to a filter type the catalyst, in powdered form, is carried or separator I6, preferably inthe form Aof acyby the vapors in dispersion or suspension in .the clone separator, for separating catalyst carried vapor stream; the catalyst is continuously sepa, 25 through the vapor line.V The separated catalyst rated from the vapors and passed to a regeneris returned through line Il to the reaction chamating chamber so that both processing and regenber. A vapor line i9 extends from eachof the eration are carried on in a, continuous manner. -separators I6.- and is provided with a branch My invention seeks to avoid certain disadvanline 2|) whichlextends to suitable fractionating tages of each of these types of operation and to equipment '(not shown) for use during theprocprovide a, method of .processing and regeneratessing period and a branch line 2l for removing ing in which certain limiting features of the combustion gases during the regenerating period. previous methods of processing and regenerat- Each of the reactors A and B is provided withing are avoided and, particularly, to provide. a a', bottom draw-off line 22 yfor the withdrawal of process requiring less expensive equipment than 3,; catalyst. These lines are provided with valves that of the prior methods. 22A and 22B. The lines 22 extend to a regener.-

In the' fixed bed operation it is necessary to ating ychamber 23 which is preferably vertically either generate iiue gas and provide flue gas cirdisposed. A-line 24 serves to introduce air o1' culation through the catalyst bed in order to oxidizing gas to the chamber 23 to eiect cornavoid undue heating of the catalyst and to pro- 40 bustion-of the carbonaceous deposit on the catvide properly controlled burning of the carbonaalyst and accomplish the reactivation thereof. A ceous deposit through the bed or to provide a line 25 extends from an upper portion 0f @ach molten salt bath to remove excess heat and thus of the reactors A and B to the chamber 23. The keep the catalyst temperature in the proper lines 25 are equipped with valves 25A;and. 25B. range. Iny accordance with my invention the re' 45 A heat exchanger 26 is provided for supplying activation of the catalyst is conducted by flowcooling to the chamber 23 to prevent overheating the catalyst in a stream of oxidizing gas and ing the catalyst during regeneration;v the heat by having the catalyst particles in dispersion or exchanger preferably serves to generate steam. suspension in'the stream of oxidizing gas the for use in the process. need for ilue gas circulation or molten salt bath Below each reactor there is provided a line 21 to controlthe Iburning is entirely eliminated. for the introduction of air or' oxidizing gas. The Moreover, the pelleting or otherwise forming of catalyst draw-off line 22. is preferably moreor the catalyst, which is required for a satisfactory less in the form ofan L to provide a downflow iixed bed oration, is not required in my process. section through which the catalyst drops from In the fluid type method it is necessary to'prothe reactor. The air line 21 lfor reactor A is provide structure of considerable height, such es high vided with a branch 28 having a valve 28Afor standpipes, in order to handle the catalyst and introducing air at the bend of the line l22 so as to 'insure delivery from the regenerating zone to aspirate the catalyst and .cause the circulation the conversion zone; my invention avoids the use thereof through the chamber23 and thence back of expensive structure of this character. The 60 to the reactor. The air line 2l for reactorB has a similar branch line 28, having a valve 28B, for introducing air at the bend of the line 22 for reactor B. Each line 2l preferably has an additional branch line 29 extending to the bottom' of its respective reactor and a branch line 30 extending to the respective downflow leg of the line 22. Air through the branch lines 29 and 30 is admitted as 'may be necessary to prevent packing of the catalyst and aerate it so that it maybe readily circulated by the aspirating stream admitted through line 28. Each reactor is provided with a line 3I` for the admission oi steam or inert gas for purging r for other purposes.

Assuming the reactor B to be in processing service and reactor A to be in regenerating service, the operation is conducted as follows:

With the valve 22B in line 22 and valve 25B in line 25 from reactor B closed, hydrocarbon vapors, heated to the desired temperature of treatment, pass through line I3 to the reactor B. In

the initial processing period at the beginning of a run catalyst is introduced from the hopper I4 to the reactor in the stream of,q hydrocarbon feed untila sufficient quantity of catalyst has been charged to the reactor after which the delivery of catalyst may be stopped while the introduction of hydrocarbon feed is continued. In succeeding processing periods make-up catalyst may be introduced from time to time as maybe needed to `maintain the desired catalyst concentration. -The comminuted'or ypowdered catalyst is mainv open so that the vapors are delivered'to the fractionator for separation into the desired products.

Thus' a continuous stream of hydrocarbon is passed through the reactor with the catalyst in dispersion or suspension in the vapor stream and the catalyst is retained in the reaction or treating zone during'the processing step.

. 4 may be necessary to maintain the desired combustion conditions. A cooling fluid is charged to the exchanger 26 to regulate the temperature of combustion during regeneration; thus water may be charged to the exchanger at a controlled rate to regulate the regenerating temperature and the resultant stean1 is employed in the process. In some cases it is advantageous to introduce steam as an additional coolant directly into contact with the iiuidized catalyst undergoing regeneration.

In the preferred method of operation the catalyst is maintained constantly in a iiuidized or dispersed condition during both processing and regeneration as well as during the periods of transition from one step to the other. Thus, at the end oi the processing period, steam or inert gas is introduced into the reactor to displace the hydrocarbon vapors and to maintain the catalyst in a suspended or dispersed condition and then, while continuing the introduction of steam or inert gas, the introduction of air is commenced and, finally, the steam or inert gas is shut oil? and t-he flow o air continued. Similarly at the end of the regenerating period steam or inert gas is and maintain the catalyst in a luidized or suspended condition until the introduction of the During the period when the treatment of the hydrocarbons is being carried on in reactor B regeneration of catalyst from a preceding processing step therein isbeing conducted in reactor A. and chamber 23. The valve in the charging line l2 is closed and the valves 22A and 25A in the lines 22 and 25, respectively, from reactor A are open and air, introduced through line 28 and valve 28A, aspirates catalyst from reactor A and establishes and maintains a cyclic circulation of catalyst through line 22, chamber 23', line 25 and reactor A so that regeneration is conducted in both reactor' A and chamber 23. Small quantities of additional air may be introduced through either or both of the lines 29 and 30 to aerate the catalyst in the lower section of the reactor and insure its withdrawal therefrom for circulation. Combustion gases pass through vapor. line I5 to the cyclone separator wherein catalyst carried by the gases is separated and returned to the reactor throughline Il for continued circulation and regeneration. The valve in line 20 is closed and the valve in line `2I is'open so that the combustion gases are removed from the system through line 2i. Airis introduced throughl the line 28 at sufficient quantity and velocity to maintain the desired circulation of catalyst and such additional air is introducedfthrough line 24 as hydrocarbon stream is underway. Thus, by the introduction of steam or inert gas, the catalyst is maintained in a fluidized or suspended state during the transitions between the several processing and regenerating periods.

Although the invention is described specifically hereinas practiced in a pair of reactors or treating vessels it will be understood that any convenient number of reactors may be employed with the several processing and regenerating periods in the several reactors in proper rotation to provide a substantially continuous delivery of processed vapors to the fractionator.

This invention is adapted-for various treatments of hydrocarbons such as catalytic cracking, reforming, hydroforming, dehydrogenation, desulfurization, isomerization, isoforming and polymerization and generally to the treatment of vapors or gases with nely divided or comminuted solid catalysts. Any of the usual fluid type catalysts may be employed. Coarse catalysts having average particle sizes of, for example, 50-100 mesh may be used to advantage, since the use of such catalysts reduces the load on theA cyclone separators and also enables re ductions-in the sizes oflequipment. The coarser catalysts are, moreover, particularly suitable for operations where high pressures are desired.-

Bead catalysts of similar particle sizes may be employed to advantage. The invention is especially adapted for the treatment of stocks which, under the conditions of treatment, are in a completely vaporousv or gaseous state.

By way of example the invention maybe described as applied to catalytic cracking. In this example the gas oil stock, free from heavy ends.

having an vendpoint of say about 700 F., isv

heated to suitable catalytic cracking tempera-- tures, such as 800 F.1000 F.. and charged as a vaporous stream to the reactor. A synthetic silica alumina catalyst in the form of a dust or powder or in the form of small beads is fed in with the vaporous stream until a suilicent quantity of catalyst has been charged to the reactor whereupon' the introduction of catalyst is stopped 'while the flow of vapors is continued. The vapors undergoing cracking pass through the cracking zone thence to the fractionatlng equipment for the recovery of the desired products. The catalyst is maintained in a suspended or dispersed condition in the vapors undergoing cracking and is retained in the reaction zone during the processing step except for such minor quantities as may pass with the vapors beyond the cyclone separator. The processing step is continued for a time which may range from minimum periods, as about ten minutes, to max- In the case` imum periods of two to four hours. of the longer periods of operation make-up catalyst may be added as needed to maintain the desired concentration of catalyst in the cracking zone. At the end of the processing period the hydrocarbon feed is switched to another reactor for processing therein and steam is introduced into the iirst reactor to displace the hydrocarbon vapors and to maintain the catalyst in a suspended state. While continuing the introduction of steam the introduction of air is commenced and, finally, the steam is shut off while the ow of air is continued. The catalyst is -v maintained in cyclic circulation while suiiicient cooling is applied to maintain the catalyst at a temperature of about 1050 F. which is adequate to eiiect satisfactory combustion of carbonacecus material without injuring the structure of the catalyst. The operation is continued with alternating periods of processing and regeneration in the several reactors and with the addition of make-up catalyst from time to time as may be required.

Although a preferred embodiment of the invention has been described herein, it will be unand reactivation of catalyst conducted in a plurality of reactors and an associated chamber used alternatively with said reactors for catalyst reactivation, the process that comprises processing the hydrocarbons in one of said reactors by charging hydrocarbon vapors into the lower portion thereof, by continuously charging the hydrocarbon vapors and passing the vapors at conversion temperature upwardly through said reactor in contact with comminuted catalyst held in suspension in the vapors to subject the vapors to catalytic conversion and by retaining catalyst. in the reactor in suspension in the current of upwardly fiowing vapors while passing the vapors overhead fromthe reactor, simultaneously reactivating used catalyst in a second reactor by establishing and maintaining a cyclic passage of the used catalyst through the latter reactor and said associated chamber in suspension in a current of oxidizing gas and by withdrawing resultant combustion gases while maintaining catalyst in cyclic passage, then discontinuing the processing in the first reactor and the reactivation in the second reactor and associated chamber, diverting the charge of hydrocarbon vapors to the second reactor and subjecting the 'vapors to processing therein in the manner of processing hereinbefore specified and subjecting the used catalyst in the rst reactor to reactivation by cyclic passage in the first reactor and said associated chamber in the manner of reactivating hereinbefore specied.

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2. In the catalytic conversion of hydrocarbons and reactivation of catalyst conducted in a plurality of reactors and an associated chamber used alternatively with said reactors `for catalyst. reactivation, the process that comprises processing the hydrocarbons in one of said reactors by charging hydrocarbon vapors into the lower portion thereof, by continuously charging the hydrocz rbon vapors and passing the vapors at conversion temperature upwardly through said reactor in `contact with comminuted catalyst held in suspension in the vapors to subject the vapors to catalytic conversion and by retaining catalyst in the reactor in suspension in the current of upwardly flowing vapors while vpassing the vapors overhead from the reactor, simultaneously reactivating used catalyst in a second reactor by establishing and maintaining a cyclic passage of the used catalyst through the latter reactor and said associated chamber in suspension in a current of oxidizing gas and by withdrawing resultant combustion gases while maintaining catalyst in cyclic passage, then discontinuing the processing in the rst reactor and the reactivation in the second reactor and associated chamber, diverting the charge of hydrocarbon vapors to the second reactor and subjecting the vapors to processing therein in the manner of processing hereinbefore specified, subjecting the used catalyst in the first reactor to reactivation by cyclic passage in the rst reactor and saidassoclated chamber in the manner of reactivating hereinbefore specified and introducing a purging gas during the transition periods from processing to reacti- Vating and from reactivating to processing to maintain the catalyst in suspension.

3. In the catalytic conversion of hydrocarbons and reactivation of catalyst conducted in a plurality of reactors and an associated chamber used alternatively with said reactors for catalyst reactivation, the process that comprises processlng the hydrocarbons in one of said reactors by charging hydrocarbon vapors into the lower portion thereof, Yby continuously charging the hydrocarbon vapors and passing the vapors at conversion temperature upwardly through said reactor in contact with comminuted catalyst held in suspension inthe vapors to subject the vapors to catalytic conversion and by` retaining catalyst in the reactor in suspension in the current of upwardly iiowing vapors while passing the vapors overhead from the reactor, simultaneously reactivating used catalyst in a second reactor by establishing and maintaining a cyclic passage of the used catalyst through the latter reactor and said associated chamber in suspension in a current of oxidizing gas, by applying cooling to a portion of said cyclic passage to maintain the desired 

